1. Field of the Invention
The invention concerns a control-circuit throttle valve.
2. Description of the Prior Art
The throttle valve must traditionally perform two tasks: first, the pressure-medium flow must be throttled depending on the position of a lifting assembly; second, the throttle position must be capable of adapting to the control loop, i.e., must be adjustable. A throttle valve is known which performs these two functions with the flow-resistor motions being decoupled from each other. In this procedure the guiding edge of a piston controls the pass-through opening of the control channel and thus takes care of regulating the hydraulic flow for the hoisting unit of a tractor. The throttling characteristic of a throttle valve, however, on account of geometry of the pass-through cross-section and the guiding edge, is dependent on the position of the piston. A uniform displacement or a uniform rotary motion of the piston causes the regulating pressure to change non-uniformly, i.e., the regulating sensitivity of the throttle valve varies with the position of the power lift. Since the power lift is always moved uniformly, it reacts in its upper range (raised position) more sensitively than in its lower working range.